On Wed, Aug 22, 2018 at 09:40:55AM -0400, Derrick Stolee wrote: > On 8/21/2018 3:06 PM, Jeff King wrote: > > The main objective of scripts in the perf framework is to > > run "test_perf", which measures the time it takes to run > > some operation. However, it can also be interesting to see > > the change in the output size of certain operations. > > > > This patch introduces test_size, which records a single > > numeric output from the test and shows it in the aggregated > > output (with pretty printing and relative size comparison). > > I'm interested in exploring this test_size mechanism. The other area that > could benefit from size testing is 'git repack', but I don't have any plans > to change our compression or delta strategies. If we _did_ look into that, > then using test_size would be a natural fit.
Yeah, I agree it would be a good tool for showing off improvements there. It may also be useful for catching regressions in topics that are trying to speed things up, but _don't_ intend to change the size. We could even do that proactively now. I.e., something like: test_perf 'repack' 'git repack -adf' test_size 'pack size' 'wc -c <.git/objects/pack/*.pack' just to see if it ever changes. But I suspect its usefulness may depend on how you are packing (e.g., is "-f" more likely to catch issues than without?). The new tests I added in this series cover packs created for fetches. There's no guarantee that will overlap with the behavior of an on-disk repack, but at least we have some generic coverage of pack-objects output sizes now. Absent any suspicion of a regression for a particular case, that's probably an acceptable canary in the coal mine. -Peff
